Steel-furnace.



I. L DIXDN.

STEEL FURNACE.

APPLICATION FILED IULY15,1916.

Patented Sept. 19, 1916.

2 SHEETS-SHEET 1.

I. Lx DIXON.

STEEL FURNACE.

APPLICATION FILED JULY I5. 1916.

2 SHEETS-SHEET 2- 3 wvewto z JOSEPH L. DIXON, 011 DETROIT, MICHIGAN.

STEEL-FURNACE.

Specification of Letters Patent.

Patented Sept. 19, 1916.

if application filed July 15, 1916. Serial No. 109,454.

T 0 all whom it may concern:

Be it known that I, Josnrn L. DIXON, a subject of the King of'Great Britain, residing at Detroit, in the county oi'VVayne and Stateof Michigan, have invented certain new and useful Improvements in Steel- Furnaces; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My present invention relates to that class of electric smelting furnaces wherein the current may be made to pass either from one electrode to another over the bath or from one or more of these either wholly or in part through the bath and furnace lining.

The object of my invention is to supply an improved construction-for electric smelting furnaces of this description whereby currents fed trom specially arranged transformers are made controllable as to their phase relations by suitable switches, so as to cause different proportions of the total current to flow through the bath and lining.

It isiafurther object of the invention to accomplish this with either three-phase or two-phase systems, and without unbalancing the load on the main leads.

Certain preferred embodiments of my invention are illustrated in the accompanying drawings, wherein- Figure 1 is a diagrammatic illustration of one form of the invention delivering two phase currents in the furnace, Figs. 2 and 3 are vector diagrams showing the different phase relations producible by use of the switches shown in Fig. 1, Fig. 4 is a diagrammatic illustration of the invention as modified for use of six upper electrodes supplied with three-phase currents and Figs. 5 and 6 are vector diagrams showing the 'diiierent phase relations producible. by use of the switches shown in Fig. 4.

In Fig. 1, the usual .heartli, crucible or container is shown at 10, the molten bath within it is shown at 11, while the four upper electrodes 12. 13, 14 and 15 project downward toward the bath through the insulating cover 16. The current which passes downward through the bath when so desired, returns through the lower electrode 17 The working current is derived from the three-phase alternating current mains, 18,

19 and 20, preferably through two transformers, 21 and 22. These may be connected to the mains in various ways, it being understood that the particular connections shown are illustrated by way of example. The transformer 22 has two secondaries, shown respectively at 23 and 23. The terminals of the secondary of one transformer, as 21, are connected to the electrodes 1.2 and 13. The terminals of the secondary 23 are connected respectively to one upper electrode, as 14, and to the lower electrode 17. The terminals of the remaining secondary, 23*, are connected as shown through two double switches 24 and 25, to the electrodes 15 and 17 respectively.

As will be clear from the drawing, the effect of the secondary 23 can be reversed with relation to the other secondary 23 by closing one or the other of the switches 24.

Or 25, the other being open. When switch 24 is closed alone, the secondaries 23 and 23* act to produce current in series through the electrodes 14 and 15, there being no current through the lower electrode 17. The vector diagram illustrating current conditions in the four electrodes will then be as shown in Fig. 2. If, on the contrary, the switch 24 be open and switch 25 be closed, the secondaries 23 and 23 will act in multiple arc, and all the current delivered by the transformer 22 will pass through the lower electrode. Fig. 3 illustrates the vector diagram representing this condition. In either of these cases there will be no unequal loading of the mains, provided the transformers 21 and 22 supply equal power.

\Vhere it is desired to use three pairs of upper electrodes, the arrangement exemplified in Fig. 4 may be used. Here an extra transformer 25 is supplied, and its secondary terminals are connected to the additional pair of upper electrodes, 27 and 28. The primary connections shown are illustrated by way of example.

In Fig. 5 is shown the vector diagram resulting from closing the switch 24 while switch 25 remains open; while Fig. 6 is the diagram resulting from closing switch 25 while switch 24 is open.

In each of the forms shown there is a pair of secondariesso arranged as to be capable of either supplying their joint power for action throilg. the bath, or, on the other hand, if desire to neutralize each other, so

far as action through the bath is concerned, so as to reduce the current through the lower electrode to zero.

In my allowed application for patent, Ser.

5N0. 90083, filed April 11th, 1916, I have shown a construction wherein these ends are attained by switches in the primary circuits, and usually this arrangement will be preferable. But, in some cases, it will be found practicable and expedient to use switches in the secondary circuits, as herein described, and this has the advantage of reducing the number of transformers employed.

What I claim is 1. An electric furnace having upper elec-. trodes in pairs and a lower electrode, main leads for supplying alternating currents, one or more transformers supplied thereby whose secondaries are connected to all but one pair of said upper electrodes, an additional transformer connected with said main leads and having two secondaries whose terminals are connected to the remaining pair of upper electrodes and to the lower electrode, and switches'interposed in said secondary connections adapted to place said secondaries either in multiple are or series through said last named pair of upper electrodes.

80 2. An electric furnace having upper electrodes in pairs and a lower electrode, main leads forsupplying three-phase alternating current, one or. more transformers supplied thereby whose secondaries are connected so as to deliver two-phase current to all but one pair of said upper electrodes, an additional'transformer connected with said main leads and having two secondaries connected to the remaining pair of upper electrodes and to the lower electrode so as to deliver two-phase current thereto, and switches interposed in said secondary connections adapted to place said secondaries either in multiple arc or series through sald last named pair of upper electrodes.

3. An electric furnace having upper electrodes in pairs and a lower electrode, main leads for supplying three-phase alternating currents, one or more transformers supplied thereby whose secondaries are connected so as to deliver twdjphase currents to all but one pair of said upper electrodes, an additional transformer connected with said main leads having two secondaries, connections from the terminals of one of said secondaries to one of said remaining upper electrodes, similar connections arranged in two reversely connected branches between the terminals of the other of said secondaries and the last upper'electrode and the lower electrode respectively, and suitable switches in said two branches of the last named connections.

In testimony whereof, I have affixed my signature. U

. J OSEPH L. DIXON.

m of thin patent may be obtained for live cents each, by addrening the "Commissioner of Intel",

Wnhlngton, D. G. 

